I have a header.php file which contains a .css file link.
header.php
.css
When I \"include\" header.php into another php file in different fo
Have a look at this answer to load css relative to the current js-file: https://stackoverflow.com/a/56580810/4865307
With this trick, you just call c1CssImport() where you like to include relative-url based css files:
c1CssImport('./ui.css');